This invention relates generally to protective locks for valves and other devices which are operated by means of wrenches, and more particularly to a tamper-proof locking system for a standard fire hydrant which precludes unauthorized use of the hydrant.
A hydrant is a connection incorporated in a water main to enable a hose to be attached and a continuous supply of water to be obtained for the purpose of extinguishing fires or washing down streets. The typical hydrant or fire plug is constituted by a discharge pipe coupled to the water main and provided with a spout and a control valve. The valve has an operating stem, usually in pentagonal form. To open the valve, the stem is engaged and turned by means of a standard wrench adapted to engage the same. Similar valves are often found on the sides of buildings to operate sprinkler systems installed in the hallways.
A very common and serious problem encountered in large municipalities having thousands of fire hydrants dispersed throughout the city is the unauthorized operation of the hydrants. The public has ready access to the hydrants, and it is a simple matter to open the valves, for all that is required is an ordinary wrench adapted to engage and turn the valve stem.
Such unauthorized use may be well-motivated, as when a hydrant is operated to create a play shower in the street on a hot summer day. But when this happens on a large scale throughout the city, the resultant drop in water pressure may have serious consequences should a fire break out. In other instances, the unauthorized use of the fire hydrant may be malicious or an act of sabotage, but whatever the intention, the fact remains that the loss in water pressure may create a hazardous condition.
Various attempts have heretofore been made to provide tamper-proof locks for fire hydrants which cannot be operated by standard wrenches. Among the various approaches to this problem are the arrangements disclosed in the Diaz U.S. Pat. No. 3,709,249, the Mihalich U.S. Pat. No. 3,456,463, the Adinolfi U.S. Pat. No. 3,453,897, the Smith U.S. Pat. No. 3,532,109, the Jester U.S. Pat. No. 3,070,115, the Sullivan U.S. Pat. No. 3,532,108 and the Quinones U.S. Pat. No. 3,626,961.
One problem with prior art locking arrangements is that in some instances a special type of hydrant is required so that it is not possible to apply the locking device to existing hydrants. The cost of manufacturing and installing special hydrants on a large scale is prohibitive. In other instances, the locking device is designed for a standard hydrant but because of its complexity, it is costly to make and difficult to operate. It must be borne in mind that when the need arises for water to quench a fire, time is of the essence and fire-fighting personnel must be in a position to operate the fire hydrant quickly and without difficulty.